defmodule Exkad.Backends.HTTP.Client do

  alias Exkad.Node.Descriptor, as: ND

  defmodule Client do
    use HTTPotion.Base

  end

  defp headers(%ND{id: id, loc: loc}) do
    ["fromloc": loc, "fromid": id]
  end

  defp transfer_headers do
    ["Content-Type": "application/json"]
  end


  defp un_json("ok"), do: :ok

  defp un_json(%{"ok" => res}) do
    {:ok, res}
  end

  defp un_json(%{"value" => %{"ok" => payload}}) do
    {:value, {:ok, payload}}
  end

  defp un_json(js), do: js

  defp from_json(%HTTPotion.Response{body: body} = response) do
    Poison.decode!(body) |> un_json
  end





  def dump(_), do: raise :not_implemented
  def describe(_), do: raise :not_implemented
  def rput(_, _, _), do: raise :not_implemented
  def rget(_, _), do: raise :not_implemented


  def ping(%ND{loc: server}, from_desc) do
    Client.start
    url = server <> "/ping"
    Client.get(url, headers(from_desc)) |> from_json
  end

  def find(%ND{loc: server}, id, from_desc) do
    Client.start
    url = server <> "/find/#{id}"
    Client.get(url, headers(from_desc)) 
      |> (fn res -> res.body end).()
      |> Poison.decode!(as: %{"ok" => [ND]})
      |> un_json
  end


  def put(%ND{loc: server}, value) do
    Client.start
    url = server <> "/item"
    Client.put(url, value, transfer_headers) |> from_json
  end

  def put_meta(%ND{loc: server}, term, ptr) do
    Client.start
    url = server <> "/item/#{ptr}/meta"
    Client.put(url, term, transfer_headers) |> from_json
  end

  def search(%ND{loc: server}, key) do
    Client.start
    url = server <> "/search/#{key}"
    Client.get(url) |> from_json    
  end

  def get(%ND{loc: server}, key) do
    Client.start
    url = server <> "/item/#{key}"
    case Client.get(url) |> from_json do
      {:value, {:ok, value}} -> 
        {:value, {:ok, value}}
      err -> err
    end

  end


  

end